Pipe lining is a modern day alternative to excavation and repair. Defects such as cracks that are identified by a CCTV survey can be patched over with a special resin induced liner in two different ways.
Patch box lining is used when a defect is localised to a specific point in the drain. A smaller liner, usually 550mm or 1000mm in length is impregnated with resin, folded and wrapped around an inflatable packer before being pushed into the drain. With the aid of CCTV equipment, the packer is pushed to an exact point to cover a specific defect in the drain. It is then inflated and stays this way until it is cured. After completion the patch box liner leaves a small section of the drain lined covering the defect. Different lengths are used depending on the size of the defect. This can be done multiple times in a line and can be a cheaper alternative to full lining or excavation and repair.
Full lining is used when a section of drainage contains too many defects for patch box lining. Installing a full liner is similar to patch box lining but in this case, the liner is cut to the exact length that the drain needs to be lined. The liner is impregnated with resin and is sent through the drain to the correct position and then inflated, where it remains until it is cured. After completion, the liner leaves a seamless new pipe surface, covering the existing defects. Guarantees on liners vary between 10 and 25 years.